Directed differentiation of pluripotent stem cells to kidney cells

Abstract

Regenerative medicine affords a promising therapeutic strategy for the treatment of patients with chronic kidney disease. Nephron progenitor cell populations exist only during embryonic kidney development. Understanding the mechanisms by which these populations arise and differentiate is integral to the challenge of generating new nephrons for therapeutic purposes. Pluripotent stem cells (PSCs), comprising embryonic stem cells, and induced pluripotent stem cells (iPSCs) derived from adults, have the potential to generate functional kidney cells and tissue. Studies in mouse and human PSCs have identified specific approaches to the addition of growth factors, including Wnt and fibroblast growth factor, that can induce PSC differentiation into cells with phenotypic characteristics of nephron progenitor populations with the capacity to form kidney-like structures. Although significant progress has been made, further studies are necessary to confirm the production of functional kidney cells and to promote their three-dimensional organization into bona fide kidney tissue. Human PSCs have been generated from patients with kidney diseases, including polycystic kidney disease, Alport syndrome, and Wilms tumor, and may be used to better understand phenotypic consequences of naturally occurring genetic mutations and to conduct "clinical trials in a dish". The capability to generate human kidney cells from PSCs has significant translational applications, including the bioengineering of functional kidney tissue, use in drug development to test compounds for efficacy and toxicity, and in vitro disease modeling.

Keywords: Pluripotent stem cell; embryonic stem cell; iPS cell; kidney cell differentiation; kidney development; kidney on a chip.

Figure 1

Directed differentiation of hPSCs into cells of the kidney lineage. Stepwise differentiation of hPSCs into embryonic and adult kidney cell types. Growth factors that have been shown to induce differentiation toward specific stages and markers characteristic of each stage of are shown.

Figure 2

Schematic diagram of protocol to generate nephron progenitor cell populations from hPSCs. Directed differentiation of hPSCs into nephron progenitor cells is divided into three discrete stages, with growth factors, culture media, and duration of treatment shown for each stage. Markers characteristic of each stage of differentiation also are listed.

Figure 3

Use of kidney disease iPSCs to investigate molecular pathophysiology. (A) Phase-contrast micrograph showing a colony of undifferentiated iPSCs derived from a patient with ADPKD. Scale bar, 50 µm. (B) Immunolocalization of PC2 and acetylated α-tubulin (AcT) in undifferentiated hPSCs. PC2 localizes to cilia in wild-type ESCs (arrow), but is absent from cilia in ADPKD iPSCs. Scale bar, 10 µm.